Various methods of remotely accessing a computing server have been used in the past. One of the first methods utilized a server and terminals. Input is entered at the terminals, transmitted to the server and the results are send back over data lines to the terminals. The terminals can be “dumb” terminals, such as a VT52, with no processing power except to display the data, or they can be smart terminals, such as an IBM 3270, which can do some basic form filling without requiring intervention of the server.
As computing power has grown cheaper, various other strategies have been used. In the X11 graphical networking protocol, a display server sends bitmaps to a display client and receives input events from the client. In the NeWS graphical networking protocol, a server sends short code segments to a client computer, the code segments perform display and input handling functions at the client and, when needed, send input to—and receive display data from—the server.
A somewhat different type of remote computer access is Internet-TV. A television set is upgraded using an electronic box so that the television may be used to access the Internet. In one system, Internet related data is transmitted to and from the electronic box using protocols which transmit data over a cable network. In some instances, the data is transmitted using a data channel provided by an MPEG compression protocol. In one system, the box is a computer, which performs the Internet communication via the cable network and which uses the television as a display. In another system, a server at a cable center, sends graphical display commands to the box and the box generates a video signal responsive to the commands. Typically, the display commands are a subset of Java or HTML. In another system, the data comprises Java scripts which are executed by the box.
Cable networks have also long been used to send video and/or audio programs on demand to a particular subscriber. The video programs are compressed before sending so that a wider bandwidth is available over the cable networks. A set-top box at each subscriber is hardwired (and/or programmed) to decompress the video program and convert it into a video signal for the television. Such video on demand may be a live performance or may be retrieved from an archive. It is also possible to view video segments via the Internet.
Generally, when video is transmitted, a same band width is allocated to a plurality of video channels. In packet based video transmission, subscribers and/or channels that require a higher data rate receive more packets per second than subscribers who need a lower data rate. A company named “iMedia” uses a method of statistical multiplexing in which bandwidth is dynamically allocated between video channels, based on signal characteristics of the video being transmitted. The allocation does not depend on the content per-se of the video channels. In fact, the statistical multiplexing is preferably affected without decompressing the images.
Related patent publications include U.S. Pat. Nos. 5,612,742, 5,687,257 and 5,115,309 and PCT publication WO 97/12486, the disclosure of which are incorporated herein by reference.
The following articles, “Polygon Assisted JPEG and MPEG Compression of Synthetic Images”, by Marc Levoy, Proceeding of Siggraph 1995, “Model Based Motion Estimation for Synthetic Animations”, by Maneesh Agrawala, Andrew C. Beers and Navin Chaddha, in ACM Multimedia 1995, and “Compression Performance of the Xremote Protocol”, by John Danskin and Pat Hanrahan, Proceedings 1994 Data Compression Conference, the disclosures of which are incorporated herein by reference, describe methods compressing animation into MPEG format, on a single machine. In these methods the compression is faster since the “video source”, the animation, is completely known.